EP3041924A1

EP3041924A1 - Device and method for obtaining phytoplankton (microalgae)

Info

Publication number: EP3041924A1
Application number: EP14789780.5A
Authority: EP
Inventors: Gabriele Tübbecke; Bernd Ihlow
Original assignee: Weber GmbH
Current assignee: Weber GmbH
Priority date: 2013-09-06
Filing date: 2014-09-03
Publication date: 2016-07-13
Anticipated expiration: 2034-09-03
Also published as: EA029127B1; EA201690518A1; DE112014004070A5; EP3041924B1; PT3041924T; WO2015032389A1; DE102013109747A1

Abstract

A device for obtaining phytoplankton (microalgae), in which a nutrient solution (3) and a plurality of plates (1) which are aligned vertically and arranged with a horizontal separation from one another are present in a housing (2), these being secured alternately either at the base or at the top of the housing (2) and not extending as far as the opposite wall, in order to form a vertically meandering flow, and the nutrient solution (3) is circulated by means of a pump (4), wherein lighting means are provided at the end of the plate (1) in the region where it is secured, and the plate (1) consists of transparent solid material into which light-scattering particles are embedded such that the light output density is approximately constant over the surface of the plate (1).

Description

Device and method for obtaining phytoplankton

(Microalgae)

The invention relates to a device for obtaining

Phytoplankton (microalgae), in which a nutrient solution and a plurality of vertically aligned and horizontally spaced plates are present in one housing, which are fixed alternately either at the bottom or at the top of the housing and do not extend to the opposite wall to a form vertically meandering flow and the nutrient solution is circulated by a pump and a method for this purpose. Devices are known, often referred to as photobioreactors, with the help of which microorganisms and in particular algae can be cultivated and propagated. Such photobioreactors use carbon dioxide, CO _2, and sunlight to grow and multiply to conduct photosynthesis. The various types and types of microorganisms that can find propagation with the help of such bioreactors is obvious. An economically highly interesting area of use of such a device is the multiplication of algae, which are usually in the water and which include a variety of different algae species of about 10,000 in number.

The economic importance of bioreactors, especially algae reactors, results from the fact that a diverse economic, in the importance of increasing use is possible. Algae contain a very high proportion of minerals and trace elements, vitamins, unsaturated fatty acids and a high proportion of carbohydrates, which they use for make food or nutrients appear usable. They are also often used as additives in cosmetics or because of their high nutritional content in medicine and in pharmacy as dietary supplements, where they are used in addition to the addition as a component as a material for the production of capsules. The freshwater algae Chlorella Vulgaris, which has been especially tested in connection with the present development, contains eg the minerals calcium, magnesium, zinc, iron, selenium as well as all essential amino acids and numerous unsaturated fatty acids. The use as a dietary supplement is particularly suitable due to the manifold health benefits. From an environmental point of view, especially the CO ₂ consumption is of interest, since the algae allow the fixation of carbon dioxide CO ₂ . This is a particularly interesting aspect with regard to emissions trading. Another possible use is the production of biofuels or hydrogen. The advantage of cultivating algae in comparison to cultivating agricultural crops is the high yield per acre, the lack of waste such as leaves and roots and the low water consumption. In addition, they are not in competition with the breeding of plants because they can also be cultivated where no agriculture would be possible, so they take the food production itself no area. But also in medicine certain types of algae are used for binding and discharging heavy metals.

The present invention addresses only those algae in the water which form the phytoplankton, the photoautotrophic part of the plankton. The term microalgae is used synonymously with the term phytoplankton. To harvest the algae, the carrier liquid must be centrifuged, because the algae do not settle by themselves due to their small size. Depending on the subsequent use, drying may be necessary.

The production itself takes place in the prior art either batchwise using a bag technique or in elaborately designed glass tube systems. It is crucial that due to the high cost resulting from the lack of economically viable large-scale process manufacturing is costly and the use of microalgae has so far remained limited to a narrow range of applications despite the existing wide range of applications.

On this basis, the invention has the object to develop a device for the production of phytoplankton, through which a much more economical production and recovery of microalgae is possible.

This object is achieved according to the invention in that on the located in the region of the attachment end face of the plate lighting means are mounted and the plate

transparent solid material is embedded in the light-scattering particles such that the density of the light emission over the surface of the plate is approximately constant.

The basic structure of the device is as follows:

In a housing is a nutrient solution for the growth and propagation of phytoplankton. During operation the concentration of the nutrient solution is due to the steady consumption of a certain reduction, which makes it necessary to supply and supplement the nutrients from time to time. In this case, there are still vertically aligned and horizontally spaced plates. Each of the plates is attached either directly or indirectly to the bottom or top of the housing and dimensioned such that the plate does not extend to the opposite wall of the housing. Accordingly, there remains a certain distance, ie a gap, through which the nutrient solution flows from the intermediate space formed by two adjacent plates into the next intermediate space, either in the area of the upper side or at the bottom of the housing. With appropriate circulation of the nutrient solution, the result is a vertical meandering flow. For the purpose of circulation, a pump is provided which is to be designed in such a way that the phytoplankton is impaired and damaged as little as possible.

In that area of the plate in which the attachment takes place, means of illumination are attached to the end face. After the plate is made of transparent solid material, the light emitted by the illuminants will enter the plate and spread there. Then the optical laws of refraction apply, which lead to a total reflection at the surface of the plate and in its interior. By embedding light-scattering particles in the plate material, the total reflection is reduced and a light emission takes place, especially at a small angle to the plate surface, resulting in a luminous surface can be produced as a result. The embedded particles have the task of selectively canceling out the total reflection at the respective locations and, in the manner of a mirror, counteracting the incident there and in its cross-section in comparison with the total area of the light. To reflect and deflect current small beams so that the light rays can then leave the plate on the surfaces. By appropriate arrangement of the particles in the interior of the plate, ie by the choice of a suitable, location-dependent particle density in the plate, it can be achieved that the density of the light emission over the entire surface is almost constant.

Once in the nutrient solution, the light unfolds its desired effect by stimulating the phytoplankton to photosynthesis in the presence of CO ₂ and thereby substantially supporting the growth and growth of the phytoplankton. The supply of and support with light gives a much higher yield of phytoplankton (microalgae).

The advantages that can be achieved by using the proposed device and by carrying out the corresponding method are considerable. The increase in yield is not only due to the fact that the large-scale introduction of light photosynthesis is supported, but also in that due to the lighting means a 24-hour operation is possible, compared to the sunlight-operated bioreactors a multiple allows for yield. A further advantage is that the location of the attachment of the illumination means towards the outside, ie in the edge area, takes place exclusively so that repair or replacement of the illumination means is readily possible due to their immediate accessibility and in particular does not require disassembly of the panels. The meandering flow through the housing in the vertical direction allows a high yield with minimal own space requirement. The term lighting means is to be interpreted generally in the sense of the invention. Thus, fluorescent tubes, incandescent lamps, halogen lamps and LEDs and OLEDs can be understood here. It is particularly advantageous here to use LEDs, which allow a frequency-selective emission with low energy consumption.

For the freshwater algae Chlorella Vulgaris, which are of particular interest here, the frequencies from the spectral range 430 +/- 10 nm are thus particularly efficient from the blue color spectrum and / or the spectral range from the red spectrum of 680 +/- 10 nm. LEDs, which emit light from this frequency range, lead to maximum effects with minimal energy consumption.

Although it is sufficient to apply only one of the aforementioned frequency ranges, it has been found to be optimal to use a mixture of 70 (red spectrum) to 30 (blue spectrum) of the abovementioned frequency spectra. It goes without saying that it is also possible to use white light which emits one or both of the frequency ranges. The disadvantage here would be that the emission source energy should be supplied, which would give rise to the emission of those frequency ranges that are of no appreciable benefit. This is disadvantageous from an energetic point of view.

As an example of the plate material acrylic glass is called, which is able to distribute the light supplied at the end face evenly and also opens the possibility to introduce light-scattering particles.

It is of particular advantage, on the surfaces of the plates which serve to emit light by means of satinization, to take an additional measure. me, which ensures a (further) homogenization of the light emission. The term "satinization" describes, according to common terminology, a surface treatment which gives rise to a "roughness" which contributes to a further homogenization and homogenization of the light. After the light leakage quantitatively on those surfaces that connect to the end faces of the plates (and not on the circumferential end faces themselves), only the large surfaces, so here the surfaces of the plates to be satined.

To maintain the meandering flow, the use of pumps is usually required. The choice of suitable pump types from the large number of available options has to be carefully monitored so that the algae in the nutrient solution are harmed or even killed as little as possible, which would have a negative impact on the performance of the system. Particularly suitable, the invention provides for the use of an eccentric screw pump.

Once the algae density has reached the desired concentration, the nutrient solution should be at least partially removed and the algae separated from the nutrient solution in a separate station. As a rule, centrifuges are used for this purpose. As a process product, the microalgae, possibly after drying, placed on the market; the remaining nutrient solution is recycled.

For this reason, it is particularly appropriate to operate the device in a closed circuit, ie to feed the nutrient solution present at the end of the device and equipped with algae back to the inlet and to repeat this process for as long as possible. until the desired algae density is enriched and the renewed (partial) discharge can take place.

To support the lighting means to be supplied by external energy supply, the natural sunlight can be used as additional measures by capturing the solar radiation and also focused on the face of the plates and directed. In this way, the lighting of the plate is supported by a free energy source, which allows the power of the lighting means to shut down and thus

Energy can be saved.

Due to the arrangement of the plates, the flow of the nutrient solution at the end face, which is opposite to the illumination means, so for example in the bottom area, led around. The same thing takes place with alternating arrangement at the top of the next plate by the nutrient solution flows over at the top. Especially in the lower part of the deflection, ie where the entire volume of nutrient solution is filled, there is reason to provide baffles in the form of cylindrical half-shells, which ensure that a largely turbulence-free flow takes place in these areas. Otherwise, there is a danger of the formation of turbulence, by which the flow impeded and hindered and the formation of a homogeneous algae growth would be weakened.

It is advantageous, in the case of the existence of baffles in addition to the flat plates and also to build these baffles according to the plates, ie from their faces, in the case of halbzylinder- shaped shells, ie from the running in the direction of the longitudinal axis edges, even there with Help of lighting means light on bring to. As a result, more intensive use and higher yield are obtained by effectively increasing the areas available for photosynthesis.

The devices according to the invention are to be dimensioned accordingly with regard to the intended power capacity. For this purpose, it is proposed to design the individual device as a module in order to be able to generate the desired power in a technically simple manner by interconnecting or arranging several individual modules in parallel. In the case of series connection of the individual modules, the circulation takes place from the last module in the direction of flow to the first module of the series, so that the nutrient solution is only returned to the first module when all modules of the series have been run through and a corresponding enrichment has taken place.

When n modules are connected in parallel, the performance increases n times.

Another measure to increase the performance of the system are sensors for detecting the temperature and / or electrical conductivity and / or the pH and / or the oxygen concentration and / or the optical density available. In this way, the actual values of the operating state can be detected and the possibility opened, by influencing the outside to drive the production parameters in an optimal state. The oxygen concentration is a measure of the ongoing photosynthesis. The optical density indicates how high the algae density is in the nutrient solution and is an indicator of when the nutrient solution with the phytoplankton (microalgae) is enriched so far that the nutrient solution must be diverted and separated from the phytoplankton. For this purpose, measures are taken to optimize as are well known and applicable in the field of control engineering.

To support the photosynthesis, it is expedient to arrange lines for feeding CO ₂ and / or lines for the suction of O ₂ .

The operation of the device takes place in such a way that first a nutrient solution, possibly already doped with phytoplankton, is introduced into the device, the nutrient solution is fed past the surfaces of the plates supplied with the outgoing light, so that there under the influence of light and photosynthesis takes place under the action of CO ₂ , which leads to the accumulation and growth of algae. These measures are on the individual plates of one and the same device or by a closed circuit, which emanates from the output of the one (first) device and the input of the next, in the construction substantially similar device, etc. leads so often through this until the desired algae density is achieved.

In order to optimize the yield, control processes are carried out in the usual way, which set the reaction parameters for increasing the efficiency. Once sufficient alimentary density is achieved, as measured by oxygen concentration and / or algae density, the nutrient solution is diverted and placed in a suitable station, e.g. with the help of a centrifuge, separated. The liquid phase is returned to the circulation, however, the algae obtained, if necessary, after a further drying, for further use.

It is understood that due to the consumption of the nutrient solution, periodic nutrients must be added. It should be clarified that a diversion of the sufficiently enriched nutrient solution from a closed production cycle and its supply to a centrifuge should represent the normal case, that nevertheless at the u. U. multi-module systems is conceivable that after passing through the last station (=

Module) the nutrient solution is completely and as a whole the separation supplied (= not closed production cycle). This possibility makes sense if at the end of the plant, i. At the last module, the desired algae density is present, so that it no longer requires a return and a new run through the system.

Further details, features and advantages of the invention can be taken from the following description part, in which embodiments of the invention will be explained in more detail with reference to the drawings. Show it:

Figure 1 shows a device according to the invention in side view Figure 2 shows a production plant, consisting of several interconnected inventive devices

FIG. 1 shows a schematic side view of the device according to the invention. It consists in its fundamental

Structure of a plurality of vertically aligned and horizontally spaced plates. 1 These plates are attached with its edge either at the top of the housing 1 a or at the bottom 1 b. In the illustrated embodiment, the plates 1 a, 1 b arranged in an alternating manner, so that in each case once below the plates 1 a, on the other above the plates 1 b a Distance to the housing 2 is maintained. Inside the housing 2 is the nutrient solution 3, which is filled at least to the extent that the filling height is above the plates 1 b fixed to the ground. With appropriate loading by means of a pump 4 is formed in the nutrient solution 3, a flow which runs meandering in the plane of the drawing. The flow moves in a vertical direction along the upper plate 1 a down, where it is deflected due to the distance of the lower edge of the bottom of the housing 2 and in the vertical direction between the just described plate 1 a and the next floor-mounted plate. 1 b flows upwards. In the upper region of the filling level of the nutrient solution 3, after a deflection in the opposite direction, the flow enters the interspace between this plate 1b and the next plate 1a fastened on top of the housing 2 in order to form essentially the same flow conditions there. as they have already been described in the entrance area. To clarify the flow conditions arrows 6 are entered. As a result, a meandering flow extending over the entire device is obtained.

In the lower area towards the bottom of the housing 2, the plates 1 b are fastened via deflection devices 5 to the housing 2, which are shaped as semi-cylindrical shells and are aligned with their axis perpendicular to the plane of the drawing. As a result, the formation of laminar flow conditions is promoted at least in this area, which represents a significant contribution to the efficiency of the entire device. The adjacent deflection meet at the edge, where they go into the plate 1 b.

Upon completion of the run, the microalgae-enriched nutrient solution 3 leaves this device, either at modular structure of a next, similar in construction device or a centrifuge for separating the microalgae to be supplied from the nutrient solution. Unregistered are the illumination means attached to the outermost edges of the plates 1, which introduce the light across the face into the plate 1 and where the light propagates due to the optically transparent properties of the plate material. In order to ensure that the light escapes over the surface of the plates, light-scattering particles are embedded in the material of the hard disks. The distribution of the light-scattering particles in the plate 1 has to be such that approximately a constant density of the light emerging over the surface of the plate 1 occurs. In the context of existing carbon dioxide, sunlight causes photosynthesis to promote the growth and proliferation of phytoplankton. For a better understanding, the entire device shown in Figure 1 is provided with the reference numeral 7. FIG. 2 is a schematic representation of a production plant with a total of four devices 7. In this case, the devices 7 are linked to one another via a series connection and are connected with one another with regard to the cycle formed by the nutrient solution 3. In order to achieve compact dimensions of the entire production plant, the devices 7 are arranged in a zigzag shape.

The entrance to the lowest device 7u is located approximately in the middle of the plant, where a cabinet is symbolically indicated. Starting from the entrance of the device 7u passes through the

Nutrient solution in meandering form the entire device and it There are formed according to the photosynthesis reactions described above, a variety of microalgae and enriched in the nutrient solution 3. Starting from the end of the lowest device 7u, which is located at the front of the entire production plant, the nutrient solution 3 is transferred to the second device 7z and acted upon its input.

After passing through the device 7z, the nutrient solution 3 is transferred to the third device 7d, the transition taking place due to the zigzag arrangement of the devices 7 in the vicinity of the inlet of the lowest device 7u.

Once in the device 7d, the nutrient solution 3 passes through the next and thus third stage. At the end thereof, the transfer of the nutrient solution 3 into the uppermost device 7o takes place in the manner described above. At the outlet of the uppermost device 7o, the nutrient solution 3 is separated, on the one hand, into the microalgae as the process end product and, on the other hand, into the nutrient solution, which is optionally returned to the inlet of the lowermost device 7u after enrichment.

The components 8 are known both in their construction and in their function known equipment and require no further explanation and they include a centrifuge, a dryer, pump units and drive and power supply units.

The arrangement shown allows in a confined space, the production of large amounts of microalgae, which is due to the structure and operation of the individual devices 7 and their arrangement and linkage relative to each other in a zigzag shape with respect to the course of the nutrient solution arrangement The result is a large-scale production plant that enables large-scale production of microalgae at low cost.

LIST OF REFERENCE NUMBERS

plates

plate fixed to the top plate attached to the bottom

casing

nutrient solution

pump

deflecting

arrows

devices

lower device

2. Device

3. Device

top device

components

Claims

claims

A device for obtaining phytoplankton (microalgae) in which a nutrient solution (3) and a plurality of vertically aligned and horizontally spaced plates (1) are present in one housing (2), alternating either at the bottom or at the top of the housing (2) are fixed and do not extend to the opposite wall to form a vertical meandering flow and the nutrient solution (3) is circulated by a pump (4), characterized in that

at the located in the region of the mounting end face of the plate (1) are mounted lighting means and

the plate (1) consists of transparent solid material in which light-scattering particles are embedded in such a way that the density of the light emission over the surface of the plate (1) is approximately constant.

Device according to claim 1, characterized in that the illumination means are LED and / or OLEDs.

Apparatus according to claim 1 or 2, characterized

in that the illumination means light from the spectral range 430 +/- 10 nm and / or from the

Emit spectral range 680 +/- 10 nm.

Apparatus according to claim 3, characterized in that both frequency ranges are emitted, it being preferred is the mixing ratio of 70:30 in favor of the

Spectral lines from the range 680 +/- 10 nm.

Device, characterized in that the material of the plate (1) is acrylic glass.

Device according to the preceding claim, characterized

characterized in that the acrylic glass is satin on the surface.

Device according to one of the preceding claims, characterized in that the pump (4) has a

Eccentric screw pump is.

Device according to one of the preceding claims, characterized in that the device identifies a leading to a centrifuge discharge.

Device according to one of the preceding claims, characterized in that arranged in the bottom region of the deflection of the nutrient solution (3) are semi-cylindrical and flow-adapted deflection devices (5).

10. Device according to one of the preceding claims, characterized in that in addition sunlight collected and introduced into the plate (1).

1 1. Device according to one of the preceding claims, characterized in that the device (7) is constructed as a module.

Device according to one of the preceding claims, characterized in that the nutrient solution (3) in the manner of a closed circuit from the output of the device (7) is returned to the input.

Device according to one of the preceding claims, characterized in that the device (7) has measuring sensors for detecting the temperature and / or electrical conductivity and / or the pH and / or the oxygen concentration and / or the optical density.

Device according to one of the preceding claims, characterized in that lines for feeding CO ₂ and / or lines for sucking O ₂ are arranged.

15. A method for operating a device according to one of

preceding claims, characterized in that - First, a phytoplankton-doped nutrient solution (3) is introduced into a housing (2),

- The nutrient solution (3) is guided past the surfaces of a plate (1), from which the radiated light emitted by the front side illuminating light exits flat and

- When sufficient algae density is achieved, a separation is carried out on the one hand the algae and on the other hand the algae-free nutrient solution (3).

16. The method according to claim 15, characterized in that

- The obtained by separating the algae nutrient solution (3) in turn the device (7) is supplied and

- That after separation, an enrichment of the nutrient solution (3) with nutrients takes place and / or the algae are fed to a drying.